Single-center randomized trial of T-reg graft alone vs T-reg graft plus tacrolimus for the prevention of acute GVHD

Abstract

Allogeneic hematopoietic cell transplantation (HCT) is a curative therapy for hematological malignancies for which graft-versus-host disease (GVHD) remains a major complication. The use of donor T-regulatory cells (Tregs) to prevent GVHD appears promising, including in our previous evaluation of an engineered graft product (T-reg graft) consisting of the timed, sequential infusion of CD34+ hematopoietic stem cells and high-purity Tregs followed by conventional T cells. However, whether immunosuppressive prophylaxis can be removed from this protocol remains unclear. We report the results of the first stage of an open-label single-center phase 2 study (NCT01660607) investigating T-reg graft in myeloablative HCT of HLA-matched and 9/10-matched recipients. Twenty-four patients were randomized to receive T-reg graft alone (n = 12) or T-reg graft plus single-agent GVHD prophylaxis (n = 12) to determine whether T-reg graft alone was noninferior in preventing acute GVHD. All patients developed full-donor myeloid chimerism. Patients with T-reg graft alone vs with prophylaxis had incidences of grade 3 to 4 acute GVHD of 58% vs 8% (P = .005) and grade 3 to 4 of 17% vs 0% (P = .149), respectively. The incidence of moderate-to-severe chronic GVHD was 28% in the T-reg graft alone arm vs 0% with prophylaxis (P = .056). Among patients with T-reg graft and prophylaxis, CD4+ T-cell-to-Treg ratios were reduced after transplantation, gene expression profiles showed reduced CD4+ proliferation, and the achievement of full-donor T-cell chimerism was delayed. This study indicates that T-reg graft with single-agent tacrolimus is preferred over T-reg graft alone for the prevention of acute GVHD. This trial was registered at www.clinicaltrials.gov as #NCT01660607.

Graphical abstract

Figure 1.

T-reg graft with single-agent prophylaxis reduces acute and chronic GVHD. (A) Incidence of grade 2 to 4 acute GVHD and (B) of moderate-to-severe GVHD in patients who received transplant with T-reg graft alone (n = 12) or T-reg graft with single-agent prophylaxis (n = 12).

Figure 2.

Immune reconstitution and donor engraftment is similar in patients receiving T-reg graft with or without single-agent prophylaxis. (A) Time to neutrophil (≥500/μL) and platelet recovery (≥ 20 × 10³/μL) in patients who received transplant with T-reg graft alone (n = 12) or T-reg graft with single-agent prophylaxis (n = 12). (B) Donor whole-blood, CD15⁺ myeloid, and CD3⁺ T-cell chimerism on day 90 after transplant in patients who received transplant with T-reg graft alone (n = 10) or T-reg graft with single-agent prophylaxis (n = 11). (C) Reconstitution of white blood cell (WBC) count, CD3⁺ T-cell count, and CD19⁺ B-cell count after transplantation in patients who received transplant with T-reg graft alone (n = 11) or T-reg graft with single-agent prophylaxis (n = 12). (D) Reconstitution of total CD4⁺ T-cell count and CD4⁺CD25⁺CD127^lo Treg cell count, and CD4⁺ T-cell–to–Treg ratio after transplantation in patients who received transplant with T-reg graft alone (n = 12) or T-reg graft with single-agent prophylaxis (n = 12). Colored lines represent linear fits of each data set. ANC, absolute neutrophil count; ns, not significant.

Figure 3.

DNA methylation and cell-cycle analysis of immune cells from patients receiving T-reg graft and SOC. (A) FOXP3 TSDR (left) and non-TSDR (right) methylation from patient whole-blood DNA collected on day 14 or 30 after transplantation from patients who received transplant with T-reg graft alone (n = 12) or T-reg graft with single-agent prophylaxis (n = 12) and compared with a contemporaneous SOC cohort (n = 11). (B) Principal component analysis and 95% confidence ellipses of cell-cycle gene expression in sorted CD4⁺ Tcon and CD4⁺ Treg from day 14 after transplantation (left) and table summarizing the number of samples according to the group and cell type identified as most closely associated with G1, G2M, or S-phase of the cell cycle (right) (SOC, n = 7; no PPX, n = 12; and PPX, n = 9). (C) Regenerating islet–derived protein 3α and suppression of tumorigenicity 2 (ST2) serum concentrations on day 7 after HCT ∗ P ≤ .05, ∗∗ P ≤ .01; ns, not significant.